        .lefttop{
            margin: 0;
            padding: 0;
            width: 18%;
            height: 80px;
            background-color: silver;
        }
        .top{
            margin: 0;
            padding: 0;
            height: 70px;
            background-color: #999999;
        }
        /*垂直导航栏*/
        ul{
            margin: 0;
            list-style-type:none;/*移除列表项前小标志*/
            padding: 0;
            width: 18%;
            height: 100%;
            position: fixed;
            background-color: #999999;
            overflow: auto;
        }
        li a{
            display: block;
            color: #000;
            padding: 8px 16px;
            text-decoration: none;
        }

        /* 鼠标移动到选项上修改背景颜色 */
        li a:hover:not(.active){
            background-color: #555;
            color: white;
        }

        li a:active{
            background-color: #99CCCC;
            color: white;
        }
        .hidden{
            display: none;
        }

        /*设置子功能背景颜色及字体*/
        .funBackgroungColor{
            background-color: silver;
            font-size: x-small;
        }

        /* 下拉按钮样式 */
        .dropbtn{
            background-color: #555;
            color: white;
            padding: 16px;
            border: none;
            cursor: pointer;
            height: 70px;
        }
        /* 容器 <div> - 需要定位下拉内容 */
        .dropdown{
            position: relative;
            display: inline-block;
        }

        /* 下拉内容 (默认隐藏) */
        .dropdown-content{
            display: none;
            position: absolute;
            background-color: #f9f9f9;
            min-width: 160px;
            box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
        }
        /* 下拉菜单的链接 */
        .dropdown-content a{
            color: black;
            padding: 12px 16px;
            text-decoration: none;
            display: block;
        }
        /* 鼠标移上去后修改下拉菜单链接颜色 */
        .dropdown-content a:hover{
            background-color: #555;
            color: white;
        }

        /* 在鼠标移上去后显示下拉菜单 */
        .dropdown:hover .dropdown-content{
            display: block;
        }

        /* 当下拉内容显示后修改下拉按钮的背景颜色 */
        .dropdown:hover .dropbtn{
            background-color: #555;
        }

        /*设置表格属性*/
        table ,th,td{
            border:1px solid black;
            border-collapse: collapse;
        }
        table{
            width:100%;
        }
        td{
            text-align: center;
        }
        a{
            text-decoration: none;
            color: white;
        }